The field survey and deformation characteristics of exit slope of Qingshuigou tunnel in the southwest of China

Abstract

The stability of the slope under excavation in various engineering is a hot issue, and both engineering disturbances and other internal factors have contributed to the instability of the slope. The study focused on the deformation characteristics mechanism of exit slope of Qingshuigou tunnel in Jiasha Town, Gejiu City, Honghe Prefecture, Yunnan, China. Field survey and monitoring are performed to reveal deformation mechanism of the exit slope, which is associated with hydrogeologic conditions, natural weathering, and excavation activities. The exit slope at the interface of the overburdened layer and bedrock has the possibility of landslide through the joint force of rainfall and artificial construction. According to the deformation characteristics of the exit slope and monitoring analysis, the results indicate that the surface displacement at the back scarp of the exit slope is larger than that at the head scarp of the exit slope. The deep displacement at the back scarp is 2–4 times of that at the head scarp of the slope. Based on the geophysical analysis, the overburdened layer mostly has low resistivity. The deformation mechanism of the exit slope is revealed ultimately based on the combined influences of hydrogeologic conditions, natural weathering, and excavation activities. Based on the deformation characteristics and mechanism of the exit slope, comprehensive stabilization treatment measures are proposed to prevent the exit slope from further deformation.